The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that does not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted to be prior art against the present disclosure.
In existing 802.11 WLANs, a wireless access point (AP) is usually configured to transmit data downlink to multiple client stations (STAs), or to receive data uplink from the multiple client STAs. The downlink and/or uplink transmission is defined by the 802.11 standards. For example, under the 802.11ax uplink (UL) multi-user (MU) MIMO, an AP may receive simultaneous data frames from more than one non-AP STAs. Such UL MUMIMO transmission is preceded by a Trigger Frame (TF) from the AP. Upon receiving a TF from the AP, the non-AP STA may transmit a trigger-based (TB) PLCP protocol data unit (PPDU) for UL MUMIMO transmission. For each TF PPDU transmission, the non-AP STA transmits within an allocated spatial stream over the allocated resource unit (RU) according to TF. However, when the client STA fails to respond to the TF, e.g., without transmitting a PPDU to the AP, the AP is not made aware that no PPDU is coming from the failed STA, and still assumes that all STAs indicated in the TF would transmit some data to the AP. In this case, when the AP attempts to decode the received data from STAs, the misassumption that the received data is from all intended STAs may lead to inaccurate decoding result and thus impair the performance of the AP receiver.